When thermal dilution method and indicator dilution method are used to measure Cerebral Blood Flow （CBF）parameters, it requires catheter insertion and timing blood collection ,which will cause some damage to the human body. To solve their invasive and complex operations, a new noninvasive and rapid method for measuring the CBF was proposed based on Fick's law and Lambert's law. On the basis of Pulse Dye Densitometry/Near Infrared Spectrometry(PDD/NIRS), Indocyanine Green(ICG) was used as an indicator, and the ICG introducing brain and arterial were calculated to obtain the CBF. In order to verify the correctness of the model, an adult rabbit was used as the experimental object. The ICG pigment was injected rapidly in rabbits, at the same time the CBF was measured by PDD-NIRS method and the CBF value was calculated. Experiment shows that the relative error of CBF measured by PDD-NIRS method is 2% to 4%, which verifies the feasibility of the proposed method. The clinical comparison experiments also demonstrate that the average errors meet the clinical diagnosis requirement. This method provides a useful way for clinical diagnosis of cardiovascular and cerebrovascular diseases and clinical cerebral blood flow monitoring.